The long-term goal of the proposed research is a better understanding of the molecular mechanism of the aging process and its relationship to changing endocrine environment. This aim will be pursued through the regulatory studies on the age- and hormone-dependent synthesis of a hepatic protein (SMP-2). SMP-2 has been identified and characterized as a biomarker for hormone action and aging. The proposed research will emphasize the following: 1) isolation and characterization of full length SMP-2 cDNA clones for two isoforms of SMP-2 using an expression vector; 2) isolation and characterization of the genomic clones for SMP-2; 3) identification of nuclear nonhistone proteins that may show high affinity for the regulatory region of SMP-2 gene; 4) identification of the SMP-2 synthesizing hepatocytes by the immunohistochemical method in order to explore possible cellular specialization in the synthesis of SMP-2; 5) producation of monoclonal antibodies to the both forms of SMP-2; 6) elucidation of the mechanism of androgenic repression of SMP-2 and its mRNA using such experiments as nuclear run off assays, and pulse-chase studies for analysis of mRNA stability; 7) exploration of possible tissue diversity in the synthesis of SMP-2 using RNA dot blot assay and immunohistochemistry; and 8) investigation of the time course of reappearance of SMP-2 at the old age, in caloric restricted rats, by measuring the SMP-2 mRNA level.